This invention relates to an improved one-piece ribbed floor pan for a vehicle bed, such as a truck bed, and the related process of manufacture.
A box of a vehicle, such as a pickup truck, is illustrated in FIG. 1. This box conventionally includes a horizontally enlarged floor or bed assembly 12 which extends sidewardly between and is joined to generally parallel and upwardly extending side panels or walls 13. The side panels 13 conventionally have wheelwell housings 14 formed therein, the latter typically projecting at least inwardly a small extent into the interior of the box. The front end of the floor assembly 12 is also rigidly joined to an upwardly-projecting front wall or panel 15, the latter extending between and being rigidly fixed to the side panels 13. The rear of the box is normally closed by a rear-panel 16, the latter conventionally being an openable tailgate 16 which is conventionally hingedly joined to the box and can swing into an open generally horizontal position wherein it is substantially flush with the floor assembly to provide access to the interior of the box.
This box, and specifically the floor or bed assembly 12, conventionally includes a horizontally enlarged main bed member 17, commonly referred to as the floor pan, which defines the actual floor of the box and extends lengthwise between the front and rear ends of the box, and has a width which normally substantially spans the width of the opening between the wheelwell housings. This main floor pan 17 is supported on a front cross rail 18, several intermediate cross rails 19, and a rear cross rail or sill member 21, the latter all extending transversely under the pan and being fixedly secured thereto, such as by spot welding. Some of these cross members, such as the front rail 18, the frontmost intermediate rail 19 and the rear sill 21 are typically fixedly secured to the vehicle frame (not shown) in a conventional manner.
The bed assembly 12 also normally includes secondary bed or floor pan members 22, the latter being positioned adjacent and fixedly joined to opposite longitudinal edges of the main floor pan 17 so as to occupy the regions of the bed disposed forwardly and rearwardly of the wheelwell housings 14.
In the pickup box as conventionally constructed, the main floor pan 17 is provided with stiffening ribs 23 which project upwardly from the pan, with a plurality of such ribs being generally uniformly sidewardly spaced apart across the width of the pan and extending longitudinally of the pan over a majority of the length thereof. These ribs, which are deformed upwardly from the pan to define a downwardly-opening channel-like cross section, generally extend rearwardly from adjacent the front free edge of the main pan 17 but the ribs normally terminate in tapered rib ends 24 which merge downwardly into the planar profile of the pan 17 at a location disposed close to but spaced forwardly a small distance from the rear free edge 25 of the pan. The rear edge portion of the main pan 17, namely the flat portion thereof which is free of the ribs, is then normally seated within a shallow recess formed in the top wall of the rear sill member 21 so as to be substantially flush with the upper surface of the sill member, with the rear pan and sill member then being suitably fixedly secured together, such as by spot welding. This arrangement enables the groovelike regions defined between adjacent ribs 23 to freely open outwardly through the rear end of the bed assembly, and hence prevent creation of pockets or recesses which would collect dirt or moisture. The secondary pan members 22 also conventionally have stiffening ribs 23 formed therein and extending longitudinally of the bed, with the stiffening ribs 23 in the secondary pan members 22 again typically terminating short of the front and rear edges of the respective pan member.
FIG. 2 illustrates therein another conventional prior art box of a vehicle, such as a pickup truck, wherein the parts thereof corresponding to FIG. 1 have been identified by the same reference numerals but with the addition of a prime (xe2x80x2) thereto. The bed assembly 12xe2x80x2 of FIG. 2 again includes an enlarged main bed member or portion 17xe2x80x2 which extends longitudinally throughout the length of the bed and defines the region which extends generally transversely between the wheelwell housings of the vehicle. The bed assembly 12xe2x80x2 also again includes secondary bed members or portions 22xe2x80x2 which occupy the regions of the bed disposed forwardly and rearwardly of the wheelwell housings 14. In this prior art construction, however, the main bed portion 17xe2x80x2 and the secondary portions 22xe2x80x2 are all integrally formed in one piece and, as is generally conventional, are provided with downwardly depending flanges which project generally longitudinally along the side edges and also along the edge of the wheelwell openings for permitting securement to the adjacent side panels or wheelwell housings. The stiffening ribs associated with both the main and secondary portions 17xe2x80x2 and 22xe2x80x2, respectively, again are formed such that the ends thereof terminate in longitudinally spaced relation from the longitudinal end edges, particularly the rear edge of the bed.
A bed assembly having the structure described above has, for a very long time, been constructed using individual members which have been stamped utilizing large forming presses. That is, the floor pan 17 (FIG. 1) or 17xe2x80x2, 22xe2x80x2 (FIG. 2) as well as the cross rails 18, 19 and 21 have been conventionally formed from flat steel sheets by positioning a precut steel sheet in a forming press which deforms the sheet to define the desired cross section of the finished member. This stamping or press-forming technique, however, even though extensively utilized for many years, possesses recognized disadvantages which have nevertheless been long tolerated in view of the belief that this was the best manner of constructing the bed assembly.
More specifically, the current and almost universally utilized technique of stamping the pan has resulted in limitations which have restricted optimum construction of the pan. For example, to stamp the floor pan 17 of FIG. 1, a large rectangular sheet must be precut in accordance with the size of the desired pan being stamped. The sheet is initially of excess width so as to provide portions along opposite edges of the sheet which can be used for clamping the sheet and holding it in position when the sheet is positioned within the press and subjected to the stamping operation. Further, during the actual stamping operation, the material of the sheet is physically deformed by the stamping die so as to permit creation of the longitudinal ribs. This necessarily results in significant changes in thickness of the sheet material due to the deformation which is caused during the rib formation process. Not only does the sheet undergo significant changes in thickness, but this change in thickness is also of varying amounts at different locations across the rib, or through the cross section of the sheet containing the ribs, so that the resulting stamped floor pan has a sheet thickness which has significant variation therein. This thickness variation can in some instances be as much as 40% to 50%. This stamping process has also been observed to result in bends or corners which are inconsistent in terms of both material thickness and included angle, and have provided a finished exterior appearance which permits such irregularities to be visually observed. This stamping operation also requires, after the pan has been stamped, that the pan be subjected to a further stamping or cutting operation which is effective for removing the clamping strip portions on opposite sides of the sheet, which strip portions are disposed of as scrap.
In view of the inherent but inconsistent thickness reductions which occur during forming of the pan by the stamping or pressing process, the pan must also be initially formed from a sheet material of greater thickness than desired so as to compensate for the expected thickness reductions which occur during the stamping operation. This increases the overall weight of the pan. Further, in view of the significant size of the main floor pan and the fact that it is deformed or stamped in basically a single pressing operation, this also necessitates utilization of an extremely large and high capacity forming press in order to accommodate both the size of the sheet and the significant pressing force encountered during the simultaneous deformation of the numerous ribs which extend longitudinally thereof. Further, these stamping operations necessarily can normally be successfully carried out only if lower strength and softer sheet steels are utilized since harder strength steels will typically split or crack if subjected to severe deformation of the type encountered in the conventional pan stamping operation.
The floor pan 17xe2x80x2, 22xe2x80x2 of FIG. 2 is basically formed in the same manner described above relative to the floor pan 17 of FIG. 1 in that it is typically formed by stamping in a large press from a single large precut rectangular sheet, which precut sheet also has the wheelwell openings precut in the sides thereof prior to stamping of the sheet in the forming press. This pan 17xe2x80x2, 22xe2x80x2, however, obviously experiences the same problems and deficiencies which result from this type of forming operation as described above.
In addition, when the pan of FIG. 2 is formed in a press, the securing flanges along the side edges and around the wheelwell are also press formed, either simultaneous with the overall pressing of the ribbed pan or in a subsequent pressing operation. In this pressing operation, the flanges are bent downwardly, and this has been observed to create manufacturing disadvantages in both the finished product and in the assembly thereof to the vehicle. For example, during this downward bending, the flange is basically swung in a cantilevered fashion about its hinge connection to the main pan member, and this results in undesired weakening due to thinning of the sheet material directly at the hinge point, and possible cracking. Further, since the flange typically extends substantially continuously along and around the wheelwell opening, the flange also tends to buckle at various points, and this causes undesired distortions in the flange. Even more-significantly, this bending of the flange makes it difficult to position the flange accurately in downwardly perpendicular relation to the sheet, and in fact there is a well observed and known tendency for the flange to spring back when the bending force is removed, thereby making it difficult to achieve the desired accuracy of perpendicularly of the flange with respect to the sheet. This lack of accurate perpendicularly consequently often makes it difficult for the flanges to be properly fit against and be welded to a wheelwell housing.
To improve on the above-described vehicle bed structure and forming method thereof, the Assignee of this application developed the improved truck bed structures and forming methods disclosed in U.S. Pat. Nos. 5,188,418, 5,544,932, 5,575,525, and 5,730,486, all of which are assigned to Pullman Industries, Inc., the Assignee hereof, and all of which are herein incorporated by reference.
In the aforesaid patents, a truck bed is disclosed including a floor pan having strengthening ribs constructed by a roll-forming process. A rear sill member cooperates with the rear edge of the floor pan and preferably has upward protrusions which interfit within and generally close the rearward ends of the ribs formed in the pan, whereby the ribs are capable of extending to the rear free edge of the pan and open longitudinally outwardly thereof to permit roll forming of the pan while facilitating proper water drainage from the bed when the pan is assembled in the vehicle, with the rear edge of the pan and specifically the ribs thus being supported and reinforced by the rear sill and the protrusions thereon.
In a continuing effort to improve on the truck bed disclosed in the aforementioned patents, the aforementioned ""486 patent additionally discloses that the rear free edge of the ribbed roll-formed floor pan can be formed with a reinforcing flange extending longitudinally along the rear free edge, which flange projects downwardly so as to effectively overlap rear surfaces defined on the protrusions and rear sill to thus provide additional reinforcement directly at the rear free edge of the pan or bed.
The improved roll-formed bed arrangement as briefly summarized above, and specifically as disclosed in the aforementioned patents, was developed primarily to permit forming of a bed assembly in a manner similar to that illustrated in FIG. 1. That is, the roll-formed bed member disclosed in the aforementioned patents was intended primarily to be the main central pan member equivalent to the main pan member 17 of FIG. 1, whereby separate secondary pan members equivalent to the secondary pan members 22 of FIG. 1 would then be used in conjunction with the main pan member, which secondary members could be formed either by roll forming or by stamping. Manufacture of the main pan member 17 by roll forming, as disclosed in the aforementioned patents, was believed to be the most satisfactory approach for using roll forming in association with a vehicle bed so as to minimize and avoid unnecessary subsequent forming operations, such as stamping operations, which were considered to be of questionable feasibility if such forming operations had to be carried out subsequent to the roll forming of the ribbed pan member. While the aforementioned patents broadly suggest roll forming of the main and secondary pans as an integral one-piece member and the subsequent processing thereof to create wheelwell openings, nevertheless the aforementioned patents do not teach how such could be accomplished and, in view of the additional difficulties presented by this proposal, significant additional development and design is and was required in order to go beyond the broad suggestion of these patents.
Accordingly, it is an object of this invention to provide an improved vehicle bed assembly, specifically a truck bed assembly, and a method of manufacturing and assembling the primary components of the truck bed assembly, so as to overcome many of the disadvantages associated with the conventional and long-utilized stamp bed assemblies as described above, and so as to also provide further improvements over the roll-formed bed assemblies disclosed in the Assignee""s aforementioned patents.
More specifically, the present invention relates to an improved vehicle bed assembly, and process of manufacture, which involves formation of a one-piece floor pan by roll forming, which floor pan has a main central pan portion as well as secondary or wing portions which are positionable forwardly and rearwardly of wheelwell openings formed in the pan adjacent opposite side edges thereof. The floor pan has strengthening ribs which extend longitudinally throughout the entire length thereof so as to terminate at the front and rear edges. The strengthening ribs extend in parallel relationship longitudinally throughout not only the main pan portion, but also longitudinally of the secondary portions, whereby these ribs terminate directly at front and rear edges of the wheelwell openings. The one-piece floor pan has the wheelwell openings formed therein, as by a controlled notching or punching operation, after the pan has been roll formed from flat sheet material, and the notching operation provides a series of flanges around the periphery of the wheelwell opening, both along the longitudinal inner edge and also on the front and rear edges thereof. The flanges are disposed in spaced relation, with some of the flanges being coplanar with top walls of the stiffening ribs, and others being coplanar with the bottom or base wall of the pan between the stiffening ribs. The roll-formed pan is subjected to a subsequent forming operation which causes the flanges to be wiped downwardly generally into a transverse or perpendicular relationship with respect to the plane of the base wall of the pan so that the flanges are positionable in adjacent and overlapping relationship to the truck inner side wall or wheelwell housing for securement thereof, such as by welding. The roll-formed ribs extend longitudinally of the pan and thus terminate not only at the rear free edge thereof, but also at the front and rear edges of the wheelwell openings.
In the preferred construction of the invention, as briefly summarized above, the rear of the one-piece pan is positioned on a rear support sill or channel member which extends transversely of the vehicle adjacent the rear of the bed. This sill preferably incorporates upper protrusions in spaced relationship therealong, which protrusions project upwardly into the rearward free ends of the stiffening ribs to support and reinforce the stiffening ribs directly adjacent the rearward free ends thereof.
The improved pan or bed member, as aforesaid, preferably provides the stiffening ribs in uniformly sidewardly-spaced relationship transversely across the main pan portion, with the ribs preferably having top walls of substantial transverse width to define the direct load-bearing surface of the bed assembly. The sidewardly spacing between adjacent ribs is typically selected so that the spacing, as defined by the base wall of the pan, is generally no greater than and preferably less than the transverse width of the top wall of the stiffening ribs to maximize the upper surface area defined by the top walls of the ribs. The configuration of the pan member and specifically the roll-formed rib pattern therein, however, is preferably selected so that the longitudinally-extending inner edge of the wheelwell is formed in a base wall as defined between two sidewardly adjacent ribs. Further, the base wall containing the longitudinally-extending inner edge of the wheelwell is, in a preferred embodiment, provided with a greater transverse width than the base walls between the other ribs so as to facilitate the creation of a flange along the longitudinally inner edge of the wheelwell, which flange can initially be formed from and coplanar with the base wall, and then subsequently deformed downwardly in generally perpendicular relationship therewith to facilitate the overall forming of the pan.
In the improved bed assembly of this invention, as aforesaid, the one-piece bed member is also preferably provided with at least two downwardly-projecting cantilevered securing flanges integrally associated with each of the front and rear edges of each wheelwell opening. These two cantilevered flanges are disposed in sidewardly-spaced relation and are of different lengths, with a longer one of the flanges being integral with the top wall of a stiffening rib which intersects the wheelwell opening, and the other flange being of shorter extent and integral with a base wall which intersects the wheelwell opening. These flanges when deformed downwardly both terminate at about the same elevation and permit securement to the vehicle, such as direct securement to the wheelwell housing.
The present invention also relates to an improved process for forming the vehicle bed, as aforesaid, specifically a one-piece roll-formed ribbed bed member having wheelwell openings formed in opposite side thereof, as well as the process for securing the bed member to the support rails and rear sill as well as other vehicle components to effectively define an assembled bed assembly.
The present invention, in addition to the improvements and advantages briefly summarized above, is also believed to provide manufacturing economies with respect to the overall manufacturing process, and permit creation of cross sections or shapes in the bed and specifically in the pan member which are not possible with stamping or press-forming operations, including the creation of sharper corners having a higher consistency with respect to both curvature and thickness.
The present invention also contemplates providing on the improved bed or pan member a modified rear edge construction which includes a generally flat and planar flange which defines the rear free edge of the bed member, and which is created by deforming, i.e., flattening, the raised ribs throughout a small longitudinal distance forwardly away from the rear free edge of the bed member. This flat and substantially planar flange can then be positioned to substantially directly overlie one of the surfaces of the rear sill. In one variation of this modification, the flange is bent downwardly to overlie a rear surface of the rear sill, whereas in another variation of this modification the flange is disposed so as to lie directly on the upper surface of the rear sill.
The present invention also includes as a modification of the rear edge construction of the bed member the forming of the ribs, directly adjacent the rear end of the bed member, with downwardly sloped configurations so that the ribs effectively taper downwardly from their maximum height to the lower base wall height as they project rearwardly, whereby the ribs effectively reduce to substantially zero height at or substantially at the rear edge of the bed member while still providing continuous longitudinally extending channels between the ribs which permit unrestricted drainage of water from the vehicle bed. The tapered rib portions at the rear ends of the ribs are preferably defined by being physically compressed or deformed, as by a pressing die, so as to cause a gradual decrease in the height of the ribs over a small longitudinal distance in the direct vicinity of the rear edge of the bed member. These tapered rib end portions can be disposed so as to either define the actual free rear edge of the bed member, or can be disposed just forwardly of and monolithically joined to a flat rear flange, as described above, so as to constitute a transition between the rear flange and the lengthwise-extending ribs of uniform height.
The processing of the roll-formed bed member to include a flat rear edge flange and/or tapered rear rib portions, as described above, can be accomplished using the same basic process for forming and making the roll-formed bed member in that the deforming of the ribs into a downward slope or taper, and the deforming of the rear rib portions into a flat flange, can be accomplished at the same workstations utilized for carrying out other forming operations on the bed member which has already been roll formed and cut to length, such as when the bed member is in the stations utilized from piercing and punching, or for deforming the securing flanges.
Other objects and purposes of the invention will be apparent to persons familiar with structures and processes of this general type upon reading the following specification and inspecting the accompanying drawings.